Bioequivalence and Bioavailability Forum • Oops.

Oops. [Regulatives / Guidelines]

posted by ElMaestro – Denmark, 2011-11-04 17:22 (4930 d 02:43 ago) – Posting: # 7610
Views: 9,037
(edited on 2011-11-04 22:36)

Hi Hs,

❝ I have no idea how to simulate CV_intra; CV_total is not what I really want (to see if reference’s different variances have an influence on the result).

Neither had I when I started this thread, but now I have and I don't think it is difficult. Our model (simplest case but not satisfying d_labes' concern):

y~Seq+Subj+Treat+Per+error

There is one error in play unless we do a mixed model. So we sample the error (intrasubject) from a normal distribution and add it to the fixed effects. We can set the fixed effects to zero for Per and Seq, and tweak the Treat's as per our wishes for T/R ratios.

Edit:
The following code possibly shows what I suggest (and I am as always probably wrong):




Per=c(1,2,3, 1,2,3, 1,2,3, 1,2,3, 1,2,3, 1,2,3, 1,2,3, 1,2,3, 1,2,3, 1,2,3, 1,2,3, 1,2,3)

Subj=c(1,1,1, 2,2,2, 3,3,3, 4,4,4, 5,5,5, 6,6,6, 7,7,7, 8,8,8, 9,9,9, 10,10,10, 11,11,11, 12,12,12)

Trt=c(1,2,3,1,2,3,1,3,2,1,3,2,2,1,3,2,1,3,2,3,1,2,3,1,3,2,1,3,2,1,3,1,2,3,1,2)

Seq=c("ABC","ABC","ABC","ABC","ABC","ABC","ACB","ACB","ACB","ACB","ACB",

"ACB","BAC","BAC","BAC","BAC","BAC","BAC","BCA","BCA","BCA","BCA","BCA",

"BCA","CBA","CBA","CBA","CBA","CBA","CBA","CAB","CAB","CAB","CAB","CAB","CAB")



intraCV =0.3 ##30 percent CV

##CVintra=sqrt(exp(MSE)-1)



MSE=log(1+intraCV^2)

Trt.effects=c(0.9, 1.0, 0.95) ## or whatever the truly should be cf. Martin's suggestion 



##a simulation loop should start here!



## now we make the y vector

AUC=rnorm(36,  mean=0, sd=sqrt(MSE)) ##first the error/noise

for (i in 1:36)

 {

   foo=Trt[i]


   AUC[i]= AUC[i]+Trt.effects[foo] ##and here we add the fixed effect

 }

##..and analyse from here

I have not debugged so it is prolly full of errors.

—
Pass or fail!
ElMaestro

Complete thread:

Anticonservativism?! ElMaestro 2010-02-06 17:10 [Regulatives / Guidelines]
- Conservativism? Helmut 2011-11-03 21:12
  - In hindsight... ElMaestro 2011-11-03 21:43
    - In hindsight... Helmut 2011-11-04 01:56
      - In hindsight... ElMaestro 2011-11-04 08:41
      - rlnorm simulates what? d_labes 2011-11-04 09:40
        
        Oops. Helmut 2011-11-04 16:05
        
        Oops.ElMaestro 2011-11-04 16:22
        
        Simulation of intra-subject variability d_labes 2011-11-07 11:16
        
        Simulation of intra-subject variability ElMaestro 2011-11-08 11:02
        
        Oops. Oops. d_labes 2011-11-25 13:54
        
        Another Oops. Helmut 2011-11-25 14:23
- Simul Ants questions d_labes 2011-11-04 15:46
  - Simul Ants questions ElMaestro 2011-11-04 16:06
  - Simul Ants questions Helmut 2011-11-04 16:09
- Liberal Conservatives d_labes 2011-11-08 11:31
  - Liberal Conservatives martin 2011-11-08 20:50
    - Liberal Conservatives Helmut 2011-11-08 22:56
      - intra-subject correlation martin 2011-11-09 09:01
        
        intra-subject correlation Helmut 2011-11-25 17:16